Sömmerda's town wall is one of the best preserved in Thuringia. The fortifications still mark the historic town center. Construction of the wall, which is visible today, began in 1589 under the supervision of Master Hans vom Hof. Originally, the natural stone wall was 1580 meters long and up to four meters high. A connection to the south led water from the Unstrut river into a ditch in front (now a green strip). Six round towers and the Erfurt Gate, built in 1395 as part of an earlier town fortification, have been preserved. These seven structures have been restored, have slate-covered roofs and a gilded tower knob. Due to demolition, collapse and construction over the centuries, the city wall is now only 1170 meters long. The Werrchentor and the Neutor (both in the southern part of the town), the Riedtor (on the Unstrut), the Wenigensömmersche Tor (Marktstraße, gate ground plan marked in the pavement) and the Weißenseer Tor (near the Volkshaus) have not been preserved.

Eye-catching features of the town wall include the Waidstein near the town wall tower 4 and several buildings belonging to the former Kronbiegel-Collenbusch family of factory owners in the Parkweg section, including the "Villa Johanna". The half-timbered building, used as a private residence, is called the "doll's house" by locals.